CONTROLLING ENGINEERING CHANGE NOTESbyBrian Willcox CFPIM of Action MRPII |
Is there any organisation which does not have changes to their product? What is more questionable is, how many companies control it in an organised way? When you consider that any change costs money and it also changes the material plan which means that you may have to change existing purchase orders or manufacturing orders. If we don't control our changes, we will order material we don't need, not order what we do need, and have obsolescence problems. |
The Change Order
Board . A well proven practical approach to this problem is for the top decision maker to chair a "change order board". This board consists of department heads of the manufacturing, marketing, development, industrial engineering, purchasing, costing, quality, materials control and scheduling. The titles could well vary depending upon the company. It is the key department heads involved with the product who should be on this board. In addition, a change note controller is appointed who does not need to understand the technical aspects of the product. If the company works on the principle that anyone can suggest changes, they should all be channelled via the change note controller and each change must be accompanied by a full set of documentation. The change note controller sends a full set of details on each proposed change to each member of the board so they can prepare for the weekly meeting. Each member of the board will be asked to comment on the proposed change. The materials manager may raise the point that material has been ordered to cover the next six months and incidentally the new part will only be available in nine months time due to the suppliers lead time. The industrial engineer could well get excited as he has just had new tooling made which would need to be replaced if the change is implemented. Jointly this group of managers make the decision considering the needs of the business. The approach of implementing a "nice to have'" must be considered from a practical business point of view. The final decision from the change order board is then passed back to the change note controller who informs the originator if it is rejected or sends out the approved change note to all interested parties if it is accepted. |
Actioning the
Change Once the change is agreed to, two actions are needed. Firstly, to provide the necessary input to introduce the change and secondly, to update the bill of material file. Generally the request for the change and the meeting's decision provide the information for the change note controller to document the required change. The big question is, who is authorised to get into the system to change the bill of material file? I believe quite strongly that manufacturing, materials or production control should not have access to update the bill of material file. My reason is, that when output is a problem, and backs are to the wall, all kinds of mysterious "temporary" changes will be made to get themselves out of trouble. The ideal situation is that two people only in the company have access to change the bills. You need a person who reports into quality or the standards department who will make the changes, but only in accordance with an approved change note. The second person, should be his or her boss, just for when sickness occurs. The bills of material are the company's master file of their products and should be given the security they deserve. Now that the principle of controlling changes is established, how do we implement them in practice?. When a change is agreed to we need to specify by date when the existing part or parts will be phased out and when the new parts are to be introduced. This is called effectivity control. There are four types of changes occurring. |
Types of
Changes 1. An immediate change. This is usually used when either there is a safety problem or a product failure is involved. The bill of material is then updated as of today's date and if the new parts are not available, the job or the shipping stops. Not a nice change, but sometimes necessary. 2. The time phased change. After considering the existing stock situation, the availability of the new part, and the planned requirement, a date is agreed to introduce the change. The mechanics of implementing both these changes is to complete the "out" date field of the existing part on the product structure record with the date of the last time the part is to be used. The new part is then added with an "in" date of the date it is to be used from. MRP will then use the correct part for the date it is planning for. This method allows for future changes to be organised in advance to allow for material availability due to lead time problems. This can also be used when we want to change the quantity of the part. 3. A change on use-up. The inventory manager's dream is to use up all existing stock of a part before using the new one. It sounds easy, but in practice it is very difficult. Some years ago I came across a method which solves this problem, and anyone with a bill of material with effectivity date control on it can use it. Example: 4. The "Mod" Change. When a set of interrelated parts need to be changed for another set of interrelated parts, the best approach is to use a mod number. Several software packages provide this facility under some name or other. Each individual part of the set to be changed is given the same modification number which is related to the parent of the bill. The effective date is against the mod number and not the part. This then allows rescheduling of the change by altering one date only. This can be extremely useful where issues or revision numbers need to be used. These concepts allow full control of our bills of material and the resulting inventory, whilst accepting that changes are a fact of life and need to be managed. |
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October 1996